Monodispersed single-walled carbon nanotubes are formed in the one-dimensional channels of AlPO4-5 crystals by pyrolysis of hydrocarbons. DC current-voltage properties were measured under magnetic field at various temperatures. The nanotubes demonstrate one-dimensional semiconducting properties. Its energy gap is determined from the experimental data to be 52 meV. A negative magnetoconductance was observed and explained as a result of bad-gap increase induced by the magnetic field.
Sun, H. D., Tang, Z. K., & Wang, J. N. (1999). Conductance of mono-sized carbon nanotubes in channels of zeolite crystal. Journal of Magnetism and Magnetic Materials, 198, 255–257. https://doi.org/10.1016/S0304-8853(98)01094-4